Biosecurity news

Understanding jellyfish in New Zealand

Large numbers of jellyfish are popping up in secluded bays in the Marlborough Sounds. Cawthron scientists are keen to find out why.

Research to better understand native jellyfish

During recent field trips, our team of biosecurity scientists have observed large numbers of jellyfish in enclosed bays of the Marlborough Sounds at the top of New Zealand's South Island.

Although not news to local residents, the presence of these peculiar creatures piqued our scientists' curiousity and they set out to find out more.

Unanswered questions

After some research they found out that there are basic unanswered ecological questions around jellyfish. For example, what is the scientific name of the most common species of jellyfish in New Zealand? Where and when do they breed? Where and how many are there in our waters? Can they interact with aquaculture activities?

Moon jellyfish

So far we know that the most common jellyfish in the Sounds is the moon jellyfish (pictured above right), of the genus Aurelia. They have a complex life cycle that includes a free swimming medusa and a benthic phase, represented by polyps that attach to hard substrates. Although harmless to humans, moon jellyfish have an important ecological role as a predator and competitor of larvae and juveniles of wild fish stocks.

Potential impacts

Swarms of medusa can have significant economic impacts for the aquaculture, tourism and fishing industries. Such swarms, on a few occasions in New Zealand, have killed thousands of farmed salmon including 200 tonnes killed in 1998 in Big Glory Bay, Southland. Several beaches around the country were also closed after large jellyfish outbreaks.

Some believe jellyfish outbreaks will become more prominent in the future, driven by overfishing, nutrient enrichment, habitat modification and climate change. Nevertheless, jellyfish remain one of the most understudied marine groups in the country. Consequently, at Cawthron we are conducting and planning research, to better understand these beautiful yet potentially harmful creatures.

Current research

Cawthron scientists are now working on research to describe morphologically and genetically the local moon jellyfish in collaboration with scientists at the University of California. Preliminary results indicated that it is a native species called Aurelia clausa.

Contact Senior Scientist Javier Atalah to find out more about this research.